Proceedings of the XIX Conference of the International Society for Posture & Gait Research pages:179-180
Conference of the International Society for Posture & Gait Research edition:19 location:Bologna date:21-25 June 2009
Altered proprioceptive control induced by inspiratory muscles fatigue in persons with and without recurrent low back pain
Introduction: Postural stability can be challenged by external and internal (e.g. respiration) perturbations. Normally the central nervous system can deal with these challenges by counteracting with small movements of multiple joints. Recent evidence suggests that the postural compensation for the respiratory disturbance may be less effective in people with low back pain (LBP). This can explain the increased postural sway and the use of a rigid proprioceptive postural control strategy in persons with LBP. Insight into the mechanisms of this postural control impairment might assist the management of LBP. The role of the respiratory muscles in postural control remains unclear, but can be studied by inducing acute fatigue of the inspiratory muscles. The aim of this study was to examine the influence of inspiratory muscles fatigue (IMF) on postural stability and proprioceptive postural control strategies in people with and without recurrent LBP.
Methods: Postural control characteristics of 16 subjects with LBP and 12 healthy subjects were evaluated both before and after IMF. To evaluate postural stability, center of pressure (CoP) displacement was determined on a force plate. Muscle vibration was used to evaluate the role of proprioceptive signals in postural control. Ratios of CoP displacement measured during triceps surae muscles vibration to that measured during lumbar paraspinal muscles vibration determined the proprioceptive postural control strategies. All trials were performed on both a stable as unstable support surface and without vision. Acute IMF was induced by breathing against an inspiratory threshold load.
Results: After IMF, healthy subjects showed a significantly larger sway compared to the unfatigued condition, while standing on the unstable support surface (p<0.05). They increased reliance upon proprioceptive signals from the ankles, which is similar to people with LBP (p<0.05). Subjects with LBP showed that same ankle steered postural control strategy in both the unfatigued and IMF states (p>0.05).
Conclusion: During postural perturbation, IMF has a disturbing effect on postural stability in healthy subjects. The use of a rigid proprioceptive postural control strategy, rather than ‘multi-segmental’ control, due to IMF, might explain this observed postural instability. This resembles the behavior of people with LBP during an unfatigued condition. These findings suggest that inspiratory muscle training associated with postural control coaching might assist in the management of recurrent LBP.
Acknowledgements: This work was supported by grants from the Fund for Scientific Research-Flanders (1.5.104.03 and G.0674.09)
1. Hodges PW et al. Exp Brain Res. 144:293-302, 2002.
2. Grimstone SK, Hodges PW. Exp Brain Res. 151:218-24, 2003.
3. Brumagne S et al. Eur Spine J. 17:1177-84, 2008.